EP4079720A1 - Production d'acide formique ou de formaldéhyde à partir de dioxyde de carbone - Google Patents

Production d'acide formique ou de formaldéhyde à partir de dioxyde de carbone Download PDF

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EP4079720A1
EP4079720A1 EP21169695.0A EP21169695A EP4079720A1 EP 4079720 A1 EP4079720 A1 EP 4079720A1 EP 21169695 A EP21169695 A EP 21169695A EP 4079720 A1 EP4079720 A1 EP 4079720A1
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solution
formic acid
formate
bicarbonate
carbon dioxide
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Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
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Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek TNO
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Priority to EP21169695.0A priority Critical patent/EP4079720A1/fr
Priority to PCT/EP2022/060640 priority patent/WO2022223746A1/fr
Priority to EP22724098.3A priority patent/EP4326701A1/fr
Publication of EP4079720A1 publication Critical patent/EP4079720A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/445—Ion-selective electrodialysis with bipolar membranes; Water splitting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B01D53/1475—Removing carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/32—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00
    • B01D53/326—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00 in electrochemical cells
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/41—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by hydrogenolysis or reduction of carboxylic groups or functional derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/41—Preparation of salts of carboxylic acids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
    • B01D2252/10—Inorganic absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

Definitions

  • the present invention relates to a process for producing formic acid or formaldehyde and a modular system for performing the process, wherein the formic acid or formaldehyde are derived from a source of carbon dioxide.
  • Direct air capture of carbon dioxide gained attention in relation to the issue of global warming and the need for sustainable chemical building blocks. For the same reasons the use of carbon dioxide from flue gasses is investigated and applied. In direct air capture technology and the technologies for capturing flue gasses carbon dioxide is obtained in pure form. Subsequently carbon dioxide is stored or converted in chemical building blocks.
  • US 2020/0038803 It is further known from US 2020/0038803 to regenerate carbon-rich amine solutions using bipolar membrane electrodialysis.
  • US 2020/0038803 describes a regeneration system for a carbon-rich amine solution produced in carbon dioxide capture from a mixed gas, which is composed of a bipolar membrane electrodialysis apparatus and a carbon dioxide removal apparatus. The resulting product is pure carbon dioxide.
  • US 2020/0038803 is silent on providing chemical building blocks such as formic acid.
  • EP 0597151 a method for preparing formic acid is disclosed, which employs a concentrated or pure source of carbon dioxide to be captured in a tertiary amine solution to form aminoformate, and subsequently an energy-intensive distillation of aminoformate to obtain formic acid.
  • the invention concerns a highly energy and cost efficient and durable process for the production of formic acid from carbon dioxide.
  • a carbon capture step is combined with a hydrogenation step to obtain formate and a bipolar membrane electrolysis step to provide a concentrated formic acid solution and to regenerate the alkaline capture liquid of the carbon capture step.
  • the inventors have for the first time combined these steps in an integrated, efficient and durable process for the production of formic acid, which may in turn be further converted in formaldehyde.
  • the invention concerns a process for the production of formic acid.
  • the invention concerns a system which is specifically designed for performing the process according to the invention.
  • the process and system according to the invention are separately described. Nonetheless, the skilled person will appreciate that everything said for the process applies also the system and everything said for the system applies also for the process.
  • the invention concerns a process for the formation of formic acid from carbon dioxide.
  • the process according the invention comprises:
  • step (a) the capture of carbon dioxide in an alkaline solution takes place.
  • Such carbon capture is known in the art and typically takes place in a scrubber, also referred to as an absorber.
  • the scrubber is fed with a source of carbon dioxide and an alkaline solution.
  • the carbon dioxide is typically fed via a gas inlet at the bottom of the scrubber and the alkaline solution is fed via a liquid inlet at the top of the scrubber.
  • the carbon dioxide that is fed to the scrubber reacts with the alkaline compound present within the scrubber and forms a bicarbonate and/or carbonate salt.
  • the formed bicarbonate and/or carbonate solution is typically discharged from the scrubber from a liquid outlet at the bottom of the scrubber.
  • the absorber is preferably an absorption column, which is preferably operated in counter-current mode.
  • the absorber is selected from the group consisting of a tray column, a packed column, a spray column and a bubble column.
  • step (a) carbon dioxide is transferred from the source of carbon dioxide to the alkaline solution.
  • the alkaline solution is a solution comprising an alkaline compound and has a pH higher than 7.0. Due to the alkali nature of the alkaline solution upon transferal most or all of the carbon dioxide is converted to carbonate and/or bicarbonate. As is known in the art the equilibrium between carbon dioxide, carbonic acid, carbonate and bicarbonate is amongst others a function of the pH of the solution.
  • the pH of the alkaline solution is above 8, more preferably above 8.5, even more preferably above 9.0.
  • the pH of the alkaline solution is between 8.0 and 14.0, more preferably between 8.5 and 13.0, most preferably between 9.0 and 12.0.
  • step (a) preferably as much as possible bicarbonate is produced in step (a).
  • the amount of carbonate subjected to step (c) can be reduced by implementation of electrolysis step (b), which is preferably performed in such situations.
  • the solution comprising carbonate and/or bicarbonate comprises at least bicarbonate and typically it contains both carbonate and bicarbonate.
  • the carbon capture step more than 30 wt.% of the carbon dioxide of the source of carbon is transferred to the alkaline solution, more preferably more than 40 wt.% of the carbon dioxide of the source of carbon dioxide is transferred to the alkaline solution, even more preferably more than 45 wt.% of the carbon dioxide of the source of carbon dioxide is transferred to the alkaline solution.
  • the process is not limited by a maximal uptake of carbon dioxide, but from an efficiency point of view, a too high uptake would lead to increased investment and operational costs needed to capture the last bit of carbon dioxide from the source of carbon dioxide.
  • the sum of carbon dioxide, carbonic acid, carbonate and bicarbonate in the solution comprising carbonate and/or bicarbonate is above 0.01 mole per liter, more preferably above 0.1 mole per liter, most preferably in the range of 1 - 10 mole per liter.
  • the amount of carbon dioxide can be calculated as carbon dioxide equivalent, wherein 1 mole of carbon dioxide, carbonic acid, carbonate and bicarbonate each count for 1 carbon dioxide equivalent and wherein the carbon dioxide equivalent can be expressed in grams of carbon dioxide.
  • the solution comprising carbonate and/or bicarbonate comprises more than 1 wt.% on total weight of total carbon dioxide equivalent, even more preferably more than 5 wt.% on total weight of total carbon dioxide equivalent, most preferably more than 10 wt.% on total weight of total carbon dioxide equivalent.
  • the alkaline solution preferably comprises one or more alkaline compounds, preferably a hydroxide salt.
  • the hydroxide salt is preferably selected from the list consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide and lithium hydroxide, more preferably wherein the alkaline solution comprises sodium hydroxide and/or potassium hydroxide.
  • These bases are well-known alkali hydroxides used in alkaline solutions for carbon dioxide absorption.
  • the alkaline solution may comprise mixtures of alkaline compounds.
  • the alkaline solution may comprise formate. The inventors surprisingly found that the presence of formate in the alkaline solution does not affect the carbon dioxide uptake, while at the same time improves the overall process efficiency for the process for producing formic acid.
  • the alkaline solution comprises 1 - 20 wt.% formate on total weight, preferably 2 - 20 wt.% formate on total weight, more preferably 4 - 15 wt.% formate on total weight. It is particularly advantageous that the alkaline solution is at least in part recycled from step (d).
  • the source of carbon dioxide may be a dilute source of carbon dioxide, instead of a source of (substantially) pure carbon dioxide.
  • the process is especially suitable for sources of carbon dioxide with low concentrations of carbon dioxide, such as flue gasses or even air. As the process does not rely on a source of pure carbon dioxide, it is highly versatile, especially in terms of location. Also, a specific additional pre-treatment to concentrate carbon dioxide is not necessary. When obtained from air, the carbon dioxide level of air directly can be lowered whilst at the same time producing a valuable product in the form of formic acid.
  • the process is also especially suitable for industrial waste streams with relative low carbon dioxide levels such as flue gasses. Due to the relative low concentration the carbon dioxide of such streams, these typically are not utilized in carbon capture processes. The current invention enables the direct use for such streams; no further carbon dioxide concentration is necessary.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 50 - 200000 ppmv, preferably in the range of 100 - 150000 ppmv, even more preferably is in the range of 200 - 120000 ppmv.
  • the unit ppmv refers to parts per million in volume.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 0.01 -25 wt.% of total weight, more preferably in the range of 0.02 - 20 wt.% of total weight, even more preferably in the range of 0.02 - 15 wt.% of total weight, most preferably in the range of 0.03 - 15 wt.% of total weight.
  • the source of carbon dioxide is air and/or flue gas.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 50 - 5000 ppmv, preferably in the range of 100 - 1000 ppmv, even more preferably is in the range of 200 - 500 ppmv.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 0.01 - 1.0 wt.% on total weight, more preferably in the range of 0.02 - 0.5 wt.% on total weight, even more preferably in the range of 0.02 - 0.1 wt.% on total weight, most preferably in the range of 0.04 - 0.08 wt.% on total weight.
  • the source of carbon dioxide is air.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 1000 - 200000 ppmv, preferably in the range of 10000 - 150000 ppmv, even more preferably is in the range of 50000 - 120000 ppmv.
  • the amount of carbon dioxide in the source of carbon dioxide is in the range of 0.5 - 20 wt.% on total weight, more preferably in the range of 1 - 15 wt.% on total weight, even more preferably in the range of 2 - 20 wt.% on total weight, most preferably in the range of 5 - 15 wt.% on total weight.
  • the source of the source of carbon dioxide is flue gas.
  • Step (a) further affords a gaseous product stream which is depleted in carbon dioxide with respect to the incoming source of carbon dioxide.
  • This gaseous product can be used as deemed fit, such as emitted to the environment.
  • the solution comprising carbonate and/or bicarbonate is subjected to the hydrogenation of step (c), optionally after an alkaline water electrolysis step (b).
  • the pH is adjusted after step (a), if needed, to be in the range of 7.0 - 11.0, more preferably in the range of 7.5 - 10.0, most preferably in the range of 8.0 - 9.0.
  • step (c) can operate with pH values outside this range, the efficacy of this step is highly improved within this pH range. The inventors found that in case the concentration of carbon dioxide in the source of carbon dioxide is very low, the pH of the resulting solution, comprising carbonate and/or bicarbonate, obtained in step (a) is high, resulting in an equilibrium lying towards carbonate.
  • the solution comprising carbonate and/or bicarbonate may be slightly acidified before it is subjected to step (c).
  • the concentration of carbon dioxide in the source of carbon dioxide is below 5000 ppmv of carbon dioxide, preferably below 1000 ppmv of carbon dioxide, most preferably even below 500 ppmv of carbon dioxide and/or when the concentration of carbon dioxide in the source of carbon dioxide is below 1 wt.% of carbon dioxide on total weight, preferably below 0.5 wt.% of carbon dioxide on total weight, most preferably below 0.1 wt.% of carbon dioxide on total weight.
  • the solution comprising carbonate and/or bicarbonate originating from step (a) is slightly acidified before it is subjected to step (c) in case the source of carbon dioxide is air.
  • the inventors realized that also for higher concentrations of carbon dioxide in the source of carbon dioxide, the pH of the solution comprising carbonate and/or bicarbonate is preferably optimized to provide an optimal feed for step (c).
  • a relative high pH of the alkaline solution is desirable during step (a).
  • the solution comprising carbonate and/or bicarbonate obtained in step (a) is acidified before step (c). This is especially advantageous when the pH of the solution comprising carbonate and/or bicarbonate obtained in step (a) is above 11.0, preferably above 10.0, most preferably above 9.0.
  • the inventors have developed a highly efficient method for adjusting the pH (acidifying) of the solution comprising carbonate and/or bicarbonate originating from step (a).
  • the pH can be lowered.
  • H 2 is generated that can be used in step (c) and/or (e) of the process according to the invention.
  • Alkaline water electrolysis is known in the art, and is typically performed in an alkaline water electrolysis reactor comprising electrodes which are suitable for electrolysis of water into H 2 and O 2 . The electrodes are separated by a membrane.
  • the alkaline water electrolysis provides H 2 at the cathode side that synergistically can be used as a source of H 2 for the hydrogenation of step (c) and/or step (e), preferably for step (c).
  • the oxidation thereof can be minimized by selection of the appropriate catalyst at the anode and anode potential.
  • suitable materials and conditions to be used e.g. from Shu etal., Environ. Sci. Technol. 2020, 54 (14), 8990-8998 .
  • the process for producing formic acid comprises step (b): subjecting the solution comprising carbonate and/or bicarbonate to alkaline water electrolysis prior to step (c), wherein carbonate present in the solution comprising carbonate and/or bicarbonate is converted into bicarbonate and H 2 O is converted into H 2 and O 2 , and wherein the H 2 formed is preferably provided as a H 2 source for the hydrogenation of step (c).
  • step (b) the solution comprising carbonate and/or bicarbonate obtained in step (a) is acidified.
  • the solution comprising carbonate and/or bicarbonate is fed on the anode side of the alkaline water electrolysis reactor.
  • step (c) the solution comprising carbonate and/or bicarbonate is subjected to a hydrogenation step, wherein it is contacted with a catalyst in the presence of H 2 gas and wherein the carbonate and/or bicarbonate is converted into formate.
  • a hydrogenation step wherein it is contacted with a catalyst in the presence of H 2 gas and wherein the carbonate and/or bicarbonate is converted into formate.
  • the bicarbonate is converted into formate by the catalyst, while at the same time the equilibrium between carbonate and bicarbonate shifts towards bicarbonate, which is then converted into formate.
  • Such conversion of bicarbonate to formate is known in the art, e.g. from Su et al. ChemSusChem, 2015, 8(5), 813-816 , and can be performed by the skilled person in any suitable way.
  • the catalyst is a hydrogenation catalyst, which is capable of catalysing a hydrogenation reaction.
  • Step (c) is typically performed in a hydrogenation reactor employing conditions effective for converting carbonate and/or bicarbonate into formate.
  • the equilibrium between carbon dioxide, carbonic acid, carbonate and bicarbonate in the solution comprising carbonate and/or bicarbonate preferably is such that bicarbonate is the dominant species.
  • at least 60 mol% of the sum of carbon dioxide, carbonic acid, carbonate and bicarbonate of the solution comprising carbonate and/or bicarbonate is bicarbonate, when subjected to step (c), more preferably at least 80 mol%, most preferably at least 90 mol%. This equilibrium depends amongst others on the pH.
  • the pH of the solution comprising carbonate and/or bicarbonate in step (c) is in the range of 7.0 - 11.0, more preferably in the range of 7.5 - 10.0, most preferably in the range of 8.0 - 9.0.
  • a solution comprising formate is obtained, also referred to herein as "hydrogenated solution".
  • the solution comprising formate comprises 4 - 30 wt.% formate on total weight, more preferably 5 - 25 wt.% formate on total weight, even more preferably 10 - 25 wt.% formate on total weight.
  • any source of H 2 gas can be used in step (c).
  • the H 2 gas originates from a renewable source.
  • the H 2 gas for step (c) originates at least in part from the electrolysis of water, preferably from the alkaline water electrolysis of step (b).
  • the product of step (c) may contain unreacted H 2 gas.
  • this residual H 2 gas is separated from the solution comprising formate in step (f).
  • the solution comprising formate originating from step (c) is subjected to step (f) to remove residual H 2 gas, preferably using a vapour-liquid separator, before it is subjected to electrodialysis of step (d), preferably wherein the removed H 2 gas is recycled to the hydrogenation of step (c).
  • a H 2 separation step may be performed in a flash drum.
  • the H 2 gas subjected to step (c) comprises a mixture of H 2 gas originating from the electrolysis of water of step (b) and a recycle from the downstream H 2 removal step (f).
  • the process for producing formic acid comprises step (d), wherein the solution comprising formate obtained in step (c) is subjected to bipolar membrane electrodialysis to obtain a concentrated formic acid solution and a recovered alkaline solution.
  • step (d) the solution comprising formate is fed to a bipolar membrane electrodialysis (BMED) cell and a concentrated formic acid solution and a recovered alkaline solution is obtained.
  • BMED involves the dissociation of water in H + and OH - within the bipolar membrane (induced by the presence of an electrical field over the bipolar membrane) combined with electrodialysis wherein ionic species are transported from one solution to another by crossing one or more selectively permeable membranes.
  • step (c) formate is removed from the solution of step (c) and protonated towards formic acid. Furthermore, the alkaline solution that is used in step (a) is recovered, and is preferably re-used in step (a).
  • BMED is excellent for obtaining a highly concentrated stream of formic acid that is not contaminated with formate from a solution comprising formate, and at the same time is excellent for recovering an alkaline solution that can be re-used in the carbon capture step (a).
  • Step (d) can be performed in any BMED reactor known in the art.
  • a BMED reactor typically comprises one or more cells. Typically, each cell comprises two bipolar membranes on the outside of the cell and one ortwo permeable membranes within the cell, forming two orthree compartments. The diluate stream enters and exits one compartment and during its residence in the compartment, ionic species are transferred over the selectively permeable membrane towards one or two concentrate compartments. If one selective permeable membrane is present, the BMED cell consists of two compartments while the presence of two selective permeable membranes gives a three-compartment BMED cell.
  • a typical arrangement of a BMED cell includes a diluate compartment and a concentrate compartment, which are separated by a cation or anion exchange membrane.
  • Rinse compartments are located between the diluate compartment and the cathode and between the concentrate compartment and the anode. In a three compartment BMED, there is also a middle compartment facing two selective permeable membranes. Bipolar membrane electrodialysis is known in the art and the application for converting formate to formic acid is known, for example from the Journal of Membrane Science 325 (2008) page 528-536 and in the Journal of Membrane Science 328 (2009) pages 75-80 .
  • a rinsing solution is fed to the cathode compartment to produce H 2 and OH -
  • a rinsing solution is fed to the anode compartment to product O 2 and H + .
  • the rinsing solution fed to both rinsing compartments is the same.
  • the formate containing stream is fed into the diluate compartment, while formate is transferred through the anion exchange membrane to the concentrate compartment. At the same time, the diluate compartment is enriched with OH - from the bipolar membrane.
  • the concentrate stream may be a loop wherein the concentration of formate increases.
  • the loop typically contains a bleed stream, as a branch to collect formic acid from the concentrate loop, as well as a feed stream to replenish the concentrate loop with water and polyelectrolytes.
  • the bleed stream comprising formic acid is preferably subjected to the hydrogenation of step (e).
  • bicarbonate ions may cross the anion exchange membrane from the diluate to the concentrate compartment, where they will recombine with H + to form CO 2 .
  • the thus formed CO 2 is stripped from the BMED reactor. Such CO 2 stripping is known in the art.
  • the solution comprising formate is fed to the diluate compartment of a two-compartment BMED cell and the diluate compartment is separated from the concentrate compartment by an anion exchange membrane.
  • the solution comprising formate may also be fed to the concentrate compartment of a two-compartment BMED cell and the diluate compartment is separated from the concentrate compartment by a cation exchange membrane, although this is less preferred.
  • the preferred configuration surprisingly gives a much lower formate contamination in the concentrated formic acid solution. This provides a high quality concentrated formic acid solution which subsequently provides high quality formaldehyde.
  • the BMED of step (d) is two-compartment BMED.
  • two-compartment BMED is more favorable in terms of energy consumption and has a more straightforward and therefore cheaper design.
  • the solution comprising formate is fed to the diluate compartment of a two-compartment BMED cell and the diluate compartment is separated from the concentrate compartment by an anion exchange membrane. It is also possible to feed the solution comprising formate to the concentrate compartment of a two-compartment BMED cell and the diluate compartment is separated from the concentrate compartment by a cation exchange membrane.
  • the solution comprising formate is deprived of formate whilst at the same time the pH of the solution is increased by the formation of OH - at the bipolar membrane facing the diluate compartment, resulting in recovery of the alkaline solution.
  • formate is accumulated that is converted in formic acid by the H + that is formed at the bipolar membrane facing the concentrate compartment.
  • step (d) does not need to be operated at the highest possible yield to have an efficient process.
  • BMED processes in which substantially all of the formate entering the reactor is converted into formic acid, to provide pure formic acid and hydroxide solutions were found to be energetically challenging.
  • the relative low conversion into formic acid during step (d) gives a recovered alkaline solution containing some formate still, which was found not to jeopardize the overall process efficiency.
  • step (a) the uptake of carbon dioxide in step (a) is not affected, nor is the effectiveness of the optional alkaline water electrolysis of step (b) and of the hydrogenation step (c). Any unconverted formate will thus be fed again to step (d), wherein it may be converted into formic acid.
  • step (d) the formic acid product stream will not contain substantial amounts of formate, the end product and overall process yield are not negatively affected by incomplete conversion of formate into formic acid during step (d).
  • the recovered alkaline solution comprises 1 - 20 wt.% formate on total weight, more preferably 2 - 20 wt.% formate on total weight, even more preferably 4 - 15 wt.% formate on total weight.
  • step (d) less than 80 % of the formate of the solution comprising formate obtained in step (c) is converted to formic acid, more preferably 10 - 70 % of the formate of the solution comprising formate obtained in step (c) is converted to formic acid, more preferably 20 - 60 % of the formate of the solution comprising formate obtained in step (c) is converted to formic acid, even more preferably 30- 60 % of the formate of the solution comprising formate obtained in step (c) is converted to formic acid.
  • the concentrated formic acid solution obtained in step (d) comprises a high amount of formic acid.
  • the concentrated formic acid solution comprises 5 wt.% or more formic acid, even more preferably 8 wt.% or more formic acid, most preferably 10 wt.% or more formic acid, based on total weight.
  • the concentrated formic acid solution preferably is a solution of 0.5 - 3 M formic acid in water, preferably 1.5 - 2.5 M formic acid in water.
  • Such a high concentration is advantageous for isolation of the formic acid and/or for further processing of the concentrated formic acid solution into for example formaldehyde.
  • Step (d) affords a concentrated formic acid solution without substantial amounts of formate, such as less than 1 wt.% on total formic acid, even more preferably less than 0.5 wt.% on total formic acid, most preferably less than 0.1 wt.% on total formic acid.
  • the purity of formic acid (i.e. formic acid content on dry weight) in the concentrated formic acid solution obtained in step (d) may be as high as 75 - 100 wt.%, preferably 80 - 95 wt.%.
  • the formic acid stream may contain electrolyte that is fed to the BMED cell. This electrolyte enters the BMED reactor comprised in the electrolyte solution.
  • electrolyte may be selected from inorganic salts, polyelectrolytes and ion exchange resins, preferably from polyelectrolytes and ion exchange resins, most preferably the electrolyte is a polyelectrolyte.
  • Suitable inorganic salts include sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide.
  • Suitable polyelectrolytes include polyionenes, polyacrylic acids, polyethyleneimines, polyacrylamides, polystyrene sulfonates, polyallylamines, carboxymethyl celluloses, polygalacturonic acids, alginic acids, polypeptides, as well as salts, derivatives, copolymers and combinations thereof.
  • Preferred polyelectrolytes include poly(sodium-4-styrenesulfonate), poly(acrylic acid-co-maleic acid), poly(allylamine hydrochloride), poly(diallyldimethyl ammonium chloride), sodium polyacrylate and sodium poly(acrylamide-2-methyl-1-propanesulfoate).
  • polyelectrolytes that may also be suitable include but are not limited to Duramax TM , Tamol TM , Romax TM and Dowex ® (Dow Chemical), Acusol TM and Acumer TM (Rohm and Haas), Dispex ® and Magnafloc ® (BASF) and Rheosiove TM and Terrablend TM (Arkema).
  • Suitable ion exchange resins include Amberlite IR120, Nafion ® PFSA Superacid Resins NR-40 and Nafion ® PFSA Superacid Resins NR-50. Polyacids are especially preferred electrolytes.
  • the electrolyte solution comprises formic acid, to have a slightly acidic pH.
  • the formic acid fed via the electrolyte solution ends up in the concentrated formic acid solution, so does not jeopardize the overall working of the process according to the invention.
  • the electrolyte solution comprises 0.1 - 5 wt.% formic acid on total weight.
  • the concentrated formic acid solution comprises, it is preferred that it comprises less than 2 wt.% inorganic salts, based on formic acid weight, preferably less than 1 wt.%, more preferably less than 0.5 wt.%, most preferably less than 0.1 wt.% inorganic salts, based on formic acid weight.
  • the formic acid obtained in step (d) is concerted into formaldehyde.
  • Formaldehyde is a valuable feedstock for the petrochemical industry and serves as a building block for fuels and for more complex chemicals.
  • the process according to the present embodiment may also be referred to as being for producing formaldehyde.
  • step (e) the concentrated formic acid solution is subjected to a hydrogenation step in the presence of a hydrogenation catalyst to obtain a formaldehyde.
  • Suitable catalysts are known in the art, and include a Pd/Ac catalyst.
  • the concentrated formic acid solution is contacted with a catalyst in the presence of H 2 gas, to obtain a concentrated formaldehyde solution.
  • step (e) is performed in the presence of a hydrogenation catalyst and employs conditions suitable for converting formic acid into formaldehyde.
  • any source of H 2 gas can be used in step (e).
  • the H 2 gas originates from a renewable source.
  • the H 2 gas for step (e) originates from electrolysis of water, such as the electrolysis of step (b).
  • the product of step (e) may contain unreacted H 2 gas.
  • this residual H 2 gas is separated from the concentrated formaldehyde solution formed in step (e).
  • the concentrated formaldehyde solution originating from step (e) is subjected to step (g) to remove residual H 2 gas, preferably using a vapour-liquid separator.
  • the H 2 gas is recycled to the hydrogenation of step (e).
  • a H 2 separation step may be performed in a flash drum.
  • the H 2 gas subjected to step (e) comprises a mixture of H 2 gas originating from the electrolysis of water, such as from step (b), and a recycle from the downstream H 2 removal step (g).
  • the invention concerns a modular system for the process for producing formic acid.
  • the modular system comprises:
  • system further comprises one or more of the following modules:
  • Module (a) is for performing step (a)
  • module (b) is for performing step (b)
  • module (c) is for performing step (c)
  • module (d) is for performing step (d)
  • module (e) is for performing step (e).
  • the modules of the system according to the invention are interconnected to allow fluid connectivity of the streams between the modules. Such fluid connectivities exist between the outlet of one module and the inlet of the subsequent module.
  • Carbon capture modules are known in the art, and any suitable carbon capture module can be used as module (a). It comprises a scrubber having a first inlet for receiving an alkaline solution, a second inlet for receiving a source of carbon dioxide, a gas outlet in the top part of the scrubber and an outlet in the bottom part of the scrubber for discharging a solution comprising carbonate and/or bicarbonate.
  • Hydrogenation reactors are known in the art, and any suitable hydrogenation reactor can be used as module (c). It comprises an inlet for receiving the solution comprising carbonate and/or bicarbonate from module (a) or (b), an inlet for receiving H 2 gas, and an outlet to discharge a formate solution.
  • the hydrogenation reactor comprises a catalyst capable of performing a hydrogenation reaction to convert bicarbonate into formate.
  • Bipolar membrane electrodialysis (BMED) reactor are known in the art, and any suitable bipolar membrane electrodialysis reactor can be used as module (d). It comprises a first inlet for receiving the solution comprising formate, a second inlet for receiving an electrolyte solution, a first outlet for discharging the concentrated formic acid solution and a second outlet for discharging a recovered alkaline solution.
  • the second outlet is in fluid connection with the first inlet of carbon capture module (a).
  • the first outlet is is in fluid connection with the first inlet of second hydrogenation reactor (e).
  • Bipolar membrane electrodialysis reactor contains one or more electrochemical cells, each comprising a diluate compartment containing a cathode, a concentrate compartment comprising an anode and a cation or anion exchange membrane separating these compartments. Each cell further comprises two bipolar membranes on the outside of the cell.
  • the bipolar membrane electrodialysis reactor is a two-compartment BMED cell, and comprises one membrane separating the two compartments. That membrane may be a cation exchange membrane or an anion exchange membrane, preferably it is an anion exchange membrane.
  • the BMED cell contains a two rinse compartments, located between the cathode and the diluate compartment and between the anode and the concentrate compartment. These rinse compartments are each equipped with a separate inlet for receiving a rinse solution and an outlet for discharging the rinse solution, and further contain outlets for discharging hydrogen gas or oxygen gas.
  • the system according to the invention may further comprise an alkaline water electrolysis module (b).
  • Alkaline water electrolysis module are known in the art, and any suitable alkaline water electrolysis module can be used as module (b). It contains one or more electrochemical cells, each containing an anode and a cathode, which may be separated be a membrane to form an anode compartment and a cathode compartment. It further comprises an inlet for receiving the solution comprising carbonate and/or bicarbonate from module (a) and an outlet for discharging an acidified solution comprising carbonate and/or bicarbonate, that is to be used as solution comprising carbonate and/or bicarbonate in module (c).
  • Module (b) typically further comprises an inlet for receiving water at the cathode side and gas outlets for discharging oxygen gas at the anode and H 2 gas at the cathode, preferably wherein the outlet for discharging H 2 gas is in fluid connection with the gas inlet of module (c) or (e), preferably module (c).
  • the system according to the invention may further comprise a second hydrogenation reactor (e), comprising a first inlet for receiving the formic acid solution from module (d), a second for receiving H 2 gas, and an outlet for discharging formaldehyde.
  • Hydrogenation reactors are known in the art, and any suitable hydrogenation reactor can be used as module (e).
  • Figure 1 depicts a process flow diagram of the process according to the invention, in which flue gas is the source of carbon dioxide, typically with a CO 2 content in the range of 0.04 - 20 wt.%.
  • Flue gas (1) and an alkaline solution (5) enter absorber (2), wherein absorption of CO 2 into the solution of step (a) takes place.
  • absorber (2) Typically, over 50 % of the CO 2 present in the source of carbon dioxide is captured during step (a).
  • a gaseous stream depleted in carbon dioxide (4) is discharged from the top of the absorber, while a solution comprising carbonate and/or bicarbonate (6) is discharged from the bottom.
  • Solution (6) is fed to hydrogenation reactor (7), together with H 2 gas (8) which is typically generated in water electrolyzer (9), which is fed with water (10) and in addition to H 2 gas also generates O 2 gas (11).
  • step (c) occurs, which typically operates with a yield of over 80 %, and the carbonate and/or bicarbonate are hydrogenated into formate (12).
  • the resulting solution comprising formate (12) that is obtained from reactor (7) is fed to BMED reactor (13).
  • Step (d) occurs in BMED reactor (13), wherein formate is converted into formic acid, and a recovered alkaline solution, which is depleted in formate (5), which usually has a pH of above 9.5, is fed back to absorber (2) as the alkaline solution.
  • a concentrated formic acid solution (16) leaves the BMED reactor (13), together with some stripped carbon dioxide (15).
  • the thus formed formic acid may be the product (17) of the process, or may be fed to hydrogenation reactor (18) to perform step (e).
  • H 2 gas (10) from water electrolyzer (9) is fed to reactor (18), and formic acid is converted into formaldehyde (19), which typically operates with a yield of over 80 %.
  • the resulting concentrated formaldehyde stream (19) is discharged from reactor (18).
  • FIG 2 depicts a process flow diagram of the process according to the invention, in which air is the source of carbon dioxide (direct air capture).
  • Air (1) and an alkaline solution (5) enter absorber (2), wherein absorption of CO 2 into the solution of step (a) takes place.
  • absorber (2) Typically, about 50 % of the CO 2 of the source of carbon dioxide is captured during step (a).
  • a gaseous stream depleted in carbon dioxide (4) is discharged from the top of the absorber, while a solution comprising carbonate and/or bicarbonate (20) is discharged from the bottom.
  • Solution (20) is subjected to alkaline water electrolysis in reactor (21).
  • a KOH solution (24) is fed into reactor (21), and electrolysis of water of step (b) affords gaseous H 2 (22) and O 2 (23), that are discharged from the electrodes.
  • the acidified solution comprising carbonate and/or bicarbonate (6) is discharged from reactor (21).
  • the H 2 gas (22) formed in reactor (21) may be fed to hydrogenation reactor (7) and/or (18).
  • additional H 2 gas (8) may be generated in water electrolyzer (9) and fed to hydrogenation reactor (7) and/or (18).
  • the acidified solution (6) obtained from reactor (21) is fed to hydrogenation reactor (7), together with H 2 gas (8) which is typically generated in water electrolyzer (9), which is fed with water (10) and in addition to H 2 gas also generates O 2 gas (11).
  • step (c) occurs, which typically operates with a yield of over 80 %, and the carbonate and/or bicarbonate are hydrogenated into formate (12).
  • the resulting solution comprising formate (12) that is obtained from reactor (7) is fed to BMED reactor (13).
  • Step (d) occurs in BMED reactor (13), wherein formate is converted into formic acid, and a recovered alkaline solution, which is depleted in formate (5), which usually has a pH of above 9.5, is fed back to absorber (2) as the alkaline solution.
  • a concentrated formic acid solution (16) leaves the BMED reactor (13), together with some stripped carbon dioxide (15).
  • the thus formed formic acid may be the product (17) of the process, or may be fed to hydrogenation reactor (18) to perform step (e).
  • H 2 gas (10) from water electrolyzer (9) is fed to reactor (18), and formic acid is converted into formaldehyde (19), which typically operates with a yield of over 80 %.
  • the resulting concentrated formaldehyde stream (19) is discharged from reactor (18).
  • the cells comprise a diluate compartment, which is the cathode compartment to which the solution comprising formate is introduced, and a concentrate compartment, which is the anode compartment to which the electrolyte solution is fed.
  • the compartments are separated by an anion exchange membrane.
  • Each compartment is bordered by a bipolar membrane. Concentration curves for all species in solution in the two compartments are provided as a function of processing time. The model produced the volume variations per compartment as a function of time, and the differential current efficiency as a function of time, which is related to the overall efficiency of the process for formic acid production from formate.
  • the governing mechanisms in the bipolar membrane electrodialysis process are the alkalinization of the diluate compartment and the concomitant acidification of the concentrate compartment due to the action of the bipolar membranes.
  • the alkalinization and acidification fluxes which are equivalent to the water splitting flux at the bipolar membrane, is regulated by the applied electric current.
  • the water splitting flux determines the migration of the different ions in the electrodialysis process. When one molecule of water is split into hydroxide anions towards the diluate compartment, and hydronium cations towards the concentrate compartment, one anion molecule crosses the anion exchange membrane from diluate to concentrate. The crossover of cations through the bipolar membrane (sodium, potassium, etc.) due to migration hinders the water splitting action in the bipolar membrane.
  • modelled phenomena in the bipolar membrane electrodialysis process are the mass transfer of formic acid through the bipolar membranes and the anion exchange membrane due to concentration gradient between compartments, the migration of monovalent ions in the direction of the electric field as a function of both the concentration in the compartment from which the ion migrates, and the applied electric current; the electro-osmotic effect of solvent transfer through anion exchange membrane from diluate to concentrate compartments, the homogeneous reactions coming from the buffer equilibria of formate - formic acid and solubilized carbon dioxide - bicarbonate - carbonate, and water auto-ionization, and the carbon dioxide desorption at the concentrate compartment when a carrier gas is bubbled at the bottom of an hypothetical buffer vessel in which the concentrate compartment stream is recirculated.
  • the model equations for these phenomena can all be found in the above publications of Jaime Ferrer et al.
  • the main assumptions of the model are the following: a constant current density is applied throughout the whole process, with no effect on the total cell potential; the model considers an infinite set of cells, diluate and concentrate compartments, being both compartments separated by an anion exchange membranes, and each cell separated from each other by a bipolar membrane, thus meaning that the electrode compartments have not been taken into account; the anion transfer rate for bicarbonate and formate through the anion exchange membranes is taken to be the same for both; only monovalent anions are transferred through the different ion exchange membranes, thus meaning specifically that carbonate does not cross any of the membranes; constant temperature has been taken throughout the whole process.
  • the described model can predict the loss of efficiency in the bipolar membrane electrodialysis process as the conversion of formate to formic acid proceeds.
  • Table 1 the different values of Differential Current Efficiency as a function of the conversion of formate present at the diluate compartment to formic at the concentrate compartment.
  • the Differential Current Efficiency is defined as the quotient between the formic acid transfer rate at the concentrate compartment and the total acidification rate at the bipolar membrane, which is the driving force of the bipolar membrane electrodialysis process.
  • initial concentrations of bicarbonate, carbonate and formate at the diluate compartment are 250, 75 and 3000 mol ⁇ m -3 , respectively; initial concentrations of bicarbonate, carbonate and formic acid at the concentrate compartment are 0, 0 and 10 mol ⁇ m -3 , respectively; constant current density applied is 250 A ⁇ m -2 , total membrane area of the bipolar membrane electrodialysis cell is 0.02 m 2 ; initial volume of the diluate and concentrate compartment solutions is 10 -4 and 10 -4 m 3 , respectively.
  • Table 1 Results of the model for the Differential Current Efficiency for formic acid removal as a function of the formate to formic acid conversion. Conversion formate to formic acid [-] Differential Current Efficiency [-] 10% 94% 20% 88% 30% 83% 40% 78% 50% 72% 60% 66%
  • the simulation as represented in table 1 demonstrate a linear decrease of differential current efficiency upon a higher conversion of formate to formic acid.
  • a loss of differential current efficiency directly relates to a higher energy usage and to a less efficient process.

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EP21169695.0A 2021-04-21 2021-04-21 Production d'acide formique ou de formaldéhyde à partir de dioxyde de carbone Ceased EP4079720A1 (fr)

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EP21169695.0A EP4079720A1 (fr) 2021-04-21 2021-04-21 Production d'acide formique ou de formaldéhyde à partir de dioxyde de carbone
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Publication number Priority date Publication date Assignee Title
EP0597151A1 (fr) 1992-11-10 1994-05-18 Universiteit Twente Procédé de préparation de l'acide formique
US20070254969A1 (en) 2005-04-15 2007-11-01 Olah George A Efficient and selective chemical recycling of carbon dioxide to methanol, dimethyl ether and derived products
US20160137573A1 (en) 2014-11-14 2016-05-19 Board Of Regents Of The Nevada System Of Higher Education, On Behalf Of The University Of Nevada, Methods and catalyst systems for carbon dioxide conversion
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EP3795237A1 (fr) * 2019-09-19 2021-03-24 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk Onderzoek TNO Formation d'acide formique à partir d'une source de dioxyde de carbone

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EP0597151A1 (fr) 1992-11-10 1994-05-18 Universiteit Twente Procédé de préparation de l'acide formique
US20070254969A1 (en) 2005-04-15 2007-11-01 Olah George A Efficient and selective chemical recycling of carbon dioxide to methanol, dimethyl ether and derived products
US20160137573A1 (en) 2014-11-14 2016-05-19 Board Of Regents Of The Nevada System Of Higher Education, On Behalf Of The University Of Nevada, Methods and catalyst systems for carbon dioxide conversion
US20200038803A1 (en) 2018-08-02 2020-02-06 University Of Science And Technology Of China Regeneration system for carbon-rich amine solutions and method for using the same
CN109758918A (zh) * 2019-02-26 2019-05-17 清华大学 一种脱除有机胺溶液中热稳定性盐的方法
EP3795237A1 (fr) * 2019-09-19 2021-03-24 Nederlandse Organisatie voor toegepast- natuurwetenschappelijk Onderzoek TNO Formation d'acide formique à partir d'une source de dioxyde de carbone

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